Figure 5.

Abdominal aorta (A, B) and retroperitoneum (C, D). A: At low magnification, inflammatory cell infiltrates are seen, and they form a so-called
“aortitis” pattern. B: At high magnification, plasma cell and eosinophil infiltrates are seen in the adventitia.
C-D: In the retroperitoneum, plasma cell and eosinophil infiltrates are seen around (C, D) and within (D, arrowheads) the peri-aortic nerve ganglions.